The battery packs for portable power tools, outdoor tools, and certain kitchen and domestic appliances may include rechargeable batteries, such as lithium, nickel cadmium and lead-acid batteries, so that they can be recharged rather than be replaced. Thereby a substantial cost saving is achieved. Some users of battery energized equipment may have need for batteries having substantially different capacities, and to properly charge batteries, different charging rates should be used to avoid damaging the batteries.
A substantial cost and space saving is realized by providing a universal charging apparatus for charging the different batteries which require different charging rates. Further, it would be advantageous for the charging apparatus to optimize the different charging rates for each battery, in order to avoid overcharging of the battery and/or minimize the charging time. In addition, it would be advantageous if the charging apparatus was adaptable to charge future battery technologies for which it may not have been programmed to charge.